Human hair is treated today in many ways with cosmetic hair preparations. These include, for example, cleaning the hair with shampoos, care and regeneration using rinses and cures, and bleaching, coloring, and reshaping the hair using coloring agents, toning agents, waving agents, and styling preparations. Agents for modifying or tinting the color of head hair play a predominant role in this context.
For temporary coloring, it is usual to use coloring or toning agents that contain so-called substantive dyes as a coloring component. These are dye molecules that absorb directly onto the substrate and do not require an oxidizing process in order to form the color. Included among these dyes are, for example, henna, which has been known since antiquity for coloring the body and hair. These color results are, as a result, much more sensitive to shampooing than are the oxidation-based colors, so that a (very often undesirable) shift in tint, or even a visible loss of color, then occurs much more quickly.
So-called oxidizing coloring agents are used for permanent, intense coloring processes with corresponding fastness properties. Such coloring agents usually contain oxidation dye precursors, so-called developer components and coupler components. The developer components, under the influence of oxidizing agents or atmospheric oxygen, form among one another, or by coupling with one or more coupler components, the actual dyes. The oxidizing coloring agents are notable as a rule for outstanding, long-lasting color results. For natural-looking colors, it is usually necessary to use a mixture of a larger number of oxidation dye precursors; in many cases, substantive dyes are also used for toning.
These coloring agents, in particular oxidizing coloring agents or hair-bleaching powders, are as a rule manufactured by manually mixing prefabricated active-substance compositions, for example two oxidizing coloring agents. Manual intermixing is, however, time- and labor-intensive, since the constituents need, for example, to be weighed out before mixing. In addition, the user may be exposed to dust when processing solid active-substance compositions.